THE CRUSTACEA OE NEW JERSEY. 191 



pair largest and distinctly emarginated in its upper part, and 

 three posterior pairs comparatively small. Eyes well developed, 

 with dark pigment. Superior antennae generally longer than 

 inferior, and provided with well-developed accessory append- 

 age. Inferior antennae rather strongly built, fiagellum in male 

 often provided with calceolae anteriorly. Oral parts normal. 

 Gnathopoda distinctly subcheliform, and more or less strongly 

 developed, being always much more powerful in male than in 

 female. Peraeopoda usually not much elongated, three posterior 

 pairs nearly equal-sized, and with basal joint laminarly ex- 

 panded. Branchial lamellae simple, pedunculated, and incubatory 

 lamellae comparatively broad. Last pair of uropoda projects 

 beyond others, rami spinous and setiferous, outer one generally 

 much larger and having small terminal joint. Telson rather 

 small and cleft at base. 



Species numerous. Widely distributed in both fresh and 

 salt water. 



Key to the species. 



a. Habitat in salt or brackish water ; accessory flagellum equals peduncle 



of first antennae. locusta 



aa. Habitat in fresh water ; accessory flagellum distinctly less than peduncle 



of first antennas. fasciatus 



Gammarus locusta (Linnaeus). 



Plates 56 and 150, Figure 5. 



Scuds. 



Cancer locusta Linnaeus, Syst. Nat., Ed. 10, 1758, p. 634. European Seas. 



Mass. record). 

 Gammarus locusta De Kay, N. Y. Fauna. Crust., VI, 1844. p. t,7 (on Gould's 



R. Rathbun, Rep. Fisher. Ind. U. S., I, 1884, P- 824. Great Egg Har- 

 bor to Labrador. 



Holmes, Bull. Bur. Fisher., XXIV, 1904 (1905), p. 500, figs. All along 



New England coast and probably considerably further south. 



M. T. Rathbun, Occas. Papers Boston Soc. N. Hist., VII, No. 5, 1905, 



p. 66. Entire coast of New England. 



Paulmier, 58th An. Rep. N. Y. State Mus., IV, 1904 (1906), p. 159, 



fig. 28. New York City. 

 Gammarus locusta Holmes, Amer. Nat., XXXVII, 1903. p. 281. Arctic 

 America to Cape Hatteras. 



